Research Project 3: Summary Specific Aims: This project will test the hypothesis that prenatal exposures to endocrine disrupting chemicals (EDCs) affect fetal growth?specifically birth weight and whether the infant is small for gestational age (SGA) at delivery?and that these adverse effects are magnified by chronic psychosocial stress. We will focus on two groups of EDCs?polybrominated diphenyl ethers (PBDEs) and perfluorinated chemicals (PFCs)?and measures of chronic psychosocial stress. First, we will evaluate the relationship between prenatal PBDE and PFC exposures and adverse birth weight outcomes (Aim 1). We will then integrate place based, perceptual, and biological measures of stress in the maternal-fetal unit to characterize chronic psychosocial stress during pregnancy and assess birth weight effects (Aim 2). Lastly, we will examine potential interactive effects of EDC and chronic psychosocial stress exposures on birth weight outcomes (Aim 3).